Techniques for configuring multiple frequency domain opportunities for sidelink feedback

Abstract

Methods, systems, and devices for wireless communications are described. In some systems, a user equipment (UE) may receive a configuration of a set of feedback channel occasions corresponding to a first sidelink data channel in a first listen-before-talk (LBT) sub-band, the set of feedback channel occasions located over multiple LBT sub-bands of an unlicensed radio frequency spectrum band. The UE may receive a data transmission over the first sidelink data channel and may determine to transmit feedback associated with the data transmission. The UE, based on the configuration of the set of feedback channel occasions, may perform LBT for each of the set of feedback channel occasions to determine which of the set of feedback channel occasions are available to the UE for transmitting the feedback associated with the data transmission. The UE may transmit feedback over one or more of the set of feedback channel occasions accordingly.

What is claimed is: 
     
       1. A method for wireless communication at a user equipment (UE), comprising:
 receiving, from a second UE, a control message including a configuration of a plurality of feedback channel occasions for transmitting feedback associated with a transmission, the plurality of feedback channel occasions corresponding to a first sidelink data channel in a first sub-band of an unlicensed radio frequency spectrum band; 
 receiving, from the second UE, the transmission over the first sidelink data channel in the first sub-band of the unlicensed radio frequency spectrum band; 
 performing, based at least in part on the configuration of the plurality of feedback channel occasions, a listen-before-talk for each of the plurality of feedback channel occasions, the plurality of feedback channel occasions associated with the transmission received from the second UE over the first sidelink data channel in the first sub-band, the plurality of feedback channel occasions in a plurality of sub-bands, the UE operable to transmit, to the second UE, the feedback associated with the transmission using one or more of the plurality of feedback channel occasions; and 
 transmitting, to the second UE, the feedback associated with the transmission over one or more feedback channel occasions of the plurality of feedback channel occasions based at least in part on performing the listen-before-talk for each of the plurality of feedback channel occasions. 
 
     
     
       2. The method of  claim 1 , wherein receiving the control message including the configuration of the plurality of feedback channel occasions comprises:
 receiving the control message including the configuration indicating a plurality of feedback channel pools, each of the plurality of feedback channel pools corresponding to one sub-band of the unlicensed radio frequency spectrum band, wherein the plurality of feedback channel occasions includes one feedback channel pool of the plurality of feedback channel pools. 
 
     
     
       3. The method of  claim 2 , wherein the configuration indicating the plurality of feedback channel pools comprises a plurality of bit vectors, each bit vector indicating a different one of the plurality of feedback channel pools. 
     
     
       4. The method of  claim 2 , wherein the plurality of feedback channel occasions are associated with groupcast feedback, the method further comprising:
 determining that a group member identifier of the UE is less than a product of a quantity of physical resource blocks of a feedback channel occasion of the plurality of feedback channel occasions and a cyclic shift value associated with the feedback channel occasion; and 
 including the feedback channel occasion in the plurality of feedback channel occasions based at least in part on determining that the group member identifier of the UE is less than the product of the quantity of physical resource blocks and the cyclic shift value. 
 
     
     
       5. The method of  claim 2 , wherein the plurality of feedback channel occasions are associated with groupcast feedback, the method further comprising:
 determining that a quantity of UEs providing the groupcast feedback is less than a product of a quantity of physical resource blocks of a feedback channel occasion of the plurality of feedback channel occasions and a cyclic shift value associated with the feedback channel occasion; and 
 including the feedback channel occasion in the plurality of feedback channel occasions based at least in part on determining that the quantity of UEs providing the groupcast feedback is less than the product of the quantity of physical resource blocks and the cyclic shift value. 
 
     
     
       6. The method of  claim 2 , wherein the plurality of feedback channel occasions are associated with groupcast feedback, the method further comprising:
 identifying that the plurality of feedback channel occasions includes a first feedback channel occasion in the first sub-band and a second feedback channel occasion in a second sub-band; 
 determining that a first product of a first quantity of physical resource blocks of the first feedback channel occasion and a first cyclic shift value associated with the first feedback channel occasion is less than a second product of a second quantity of physical resource blocks of the second feedback channel occasion and a second cyclic shift value associated with the second feedback channel occasion; and 
 including the first feedback channel occasion and the second feedback channel occasion in the plurality of feedback channel occasions based at least in part on determining that the first product is less than the second product. 
 
     
     
       7. The method of  claim 1 , wherein receiving the control message including the configuration of the plurality of feedback channel occasions comprises:
 receiving the control message including the configuration indicating an index associated with a second sub-band and an offset value between the first sub-band and the second sub-band, wherein the plurality of feedback channel occasions include a first feedback channel occasion located in the first sub-band and a second feedback channel occasion located in the second sub-band. 
 
     
     
       8. The method of  claim 7 , wherein the transmission is a unicast transmission, the method further comprising:
 detecting a second unicast transmission over a second sidelink data channel in the second sub-band based at least in part on the index associated with the second sub-band; and 
 selecting the first feedback channel occasion and the second feedback channel occasion as two of the plurality of feedback channel occasions based at least in part on detecting the second unicast transmission in the second sub-band and a formula. 
 
     
     
       9. The method of  claim 8 , wherein the formula comprises a first product of a summation of an identifier associated with the second UE from which the transmission is received and the offset value between the first sub-band and the second sub-band and a modulo operation of a second product of a quantity of physical resource blocks of the first feedback channel occasion and a cyclic shift value associated with the first feedback channel occasion. 
     
     
       10. The method of  claim 1 , wherein transmitting the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises:
 transmitting the feedback over each feedback channel occasion of the plurality of feedback channel occasions that is associated with a successful listen-before-talk and that is located in an earliest symbol period including a feedback channel occasion. 
 
     
     
       11. The method of  claim 1 , further comprising:
 receiving a configuration indicating a primary feedback channel occasion and one or more secondary feedback channel occasions of the plurality of feedback channel occasions, wherein transmitting the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises:
 transmitting the feedback over the primary feedback channel occasion or over any of the one or more secondary feedback channel occasions based at least in part on whether the primary feedback channel occasion is associated with a successful listen-before-talk. 
 
 
     
     
       12. The method of  claim 1 , further comprising:
 receiving a configuration indicating a priority of the plurality of feedback channel occasions, wherein transmitting the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises:
 transmitting the feedback over a feedback channel occasion of the plurality of feedback channel occasions that has a highest priority and that is associated with a successful listen-before-talk. 
 
 
     
     
       13. The method of  claim 1 , wherein transmitting the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises:
 transmitting the feedback over each feedback channel occasion of the plurality of feedback channel occasions that is associated with a successful listen-before-talk. 
 
     
     
       14. The method of  claim 1 , wherein transmitting the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises:
 transmitting the feedback over a first feedback channel occasion within a same channel occupancy time of the transmission based at least in part on a cyclic prefix extension. 
 
     
     
       15. The method of  claim 14 , further comprising:
 determining that a priority of the transmission satisfies a threshold priority, that the first feedback channel occasion is an only feedback channel occasion that satisfies a packet delay budget of the transmission, that the first feedback channel occasion is in a last symbol period including a feedback channel occasion, that previous cyclic prefix extensions have occurred below a threshold amount, that the first feedback channel occasion is configured for transmitting the feedback within the same channel occupancy time, or any combination thereof, wherein transmitting the feedback over the first feedback channel occasion within the same channel occupancy time of the transmission is based at least in part on the determining. 
 
     
     
       16. A method for wireless communication at a user equipment (UE), comprising:
 transmitting, to a second UE, a control message including a configuration of a plurality of feedback channel occasions in a plurality of sub-bands of an unlicensed radio frequency spectrum band, the plurality of feedback channel occasions for feedback associated with a transmission and corresponding to a first sidelink data channel in a first sub-band of the unlicensed radio frequency spectrum band; 
 transmitting, to the second UE, the transmission over the first sidelink data channel in the first sub-band of the unlicensed radio frequency spectrum band, the plurality of feedback channel occasions associated with the transmission transmitted to the second UE over the first sidelink data channel in the first sub-band, the UE operable to receive, from the second UE, the feedback associated with the transmission using one or more of the plurality of feedback channel occasions; and 
 receiving, from the second UE, the feedback associated with the transmission over one or more feedback channel occasions of the plurality of feedback channel occasions based at least in part on a listen-before-talk for each of the plurality of feedback channel occasions, wherein the listen-before-talk for each of the plurality of feedback channel occasions is based at least in part on the configuration of the plurality of feedback channel occasions. 
 
     
     
       17. The method of  claim 16 , wherein transmitting the control message including the configuration of the plurality of feedback channel occasions comprises:
 transmitting the control message including the configuration indicating a plurality of feedback channel pools, each of the plurality of feedback channel pools corresponding to one sub-band of the unlicensed radio frequency spectrum band, wherein the plurality of feedback channel occasions includes one feedback channel pool of the plurality of feedback channel pools. 
 
     
     
       18. The method of  claim 17 , wherein the configuration indicating the plurality of feedback channel pools comprises a plurality of bit vectors, each bit vector indicating a different one of the plurality of feedback channel pools. 
     
     
       19. The method of  claim 16 , wherein transmitting the control message including the configuration of the plurality of feedback channel occasions comprises:
 transmitting the control message including the configuration indicating an index associated with a second sub-band and an offset value between the first sub-band and the second sub-band, wherein the plurality of feedback channel occasions include a first feedback channel occasion located in the first sub-band and a second feedback channel occasion located in the second sub-band. 
 
     
     
       20. The method of  claim 16 , wherein receiving the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises:
 receiving the feedback over each feedback channel occasion of the plurality of feedback channel occasions that is associated with a successful listen-before-talk and that is located in an earliest symbol period including a feedback channel occasion. 
 
     
     
       21. The method of  claim 16 , wherein:
 transmitting the control message comprises transmitting the configuration indicating a primary feedback channel occasion and one or more secondary feedback channel occasions of the plurality of feedback channel occasions; and 
 receiving the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises receiving the feedback over the primary feedback channel occasion or over any of the one or more secondary feedback channel occasions based at least in part on whether the primary feedback channel occasion is associated with a successful listen-before-talk. 
 
     
     
       22. The method of  claim 16 , wherein:
 transmitting the control message comprises transmitting the configuration indicating a priority of the plurality of feedback channel occasions; and 
 receiving the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises receiving the feedback over a feedback channel occasion of the plurality of feedback channel occasions that has a highest priority and that is associated with a successful listen-before-talk. 
 
     
     
       23. The method of  claim 16 , wherein receiving the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises:
 receiving the feedback over each feedback channel occasion of the plurality of feedback channel occasions that is associated with a successful listen-before-talk. 
 
     
     
       24. The method of  claim 16 , wherein receiving the feedback associated with the transmission over the one or more feedback channel occasions of the plurality of feedback channel occasions comprises:
 receiving the feedback over a first feedback channel occasion within a same channel occupancy time of the transmission based at least in part on a cyclic prefix extension. 
 
     
     
       25. An apparatus for wireless communication at a user equipment (UE), comprising:
 a processor; 
 memory coupled with the processor; and 
 instructions stored in the memory and executable by the processor to cause the apparatus to:
 receive, from a second UE, a control message including a configuration of a plurality of feedback channel occasions for transmitting feedback associated with a transmission, the plurality of feedback channel occasions corresponding to a first sidelink data channel in a first sub-band of an unlicensed radio frequency spectrum band; 
 receive, from the second UE, the transmission over the first sidelink data channel in the first sub-band of the unlicensed radio frequency spectrum band; 
 perform, based at least in part on the configuration of the plurality of feedback channel occasions, a listen-before-talk for each of the plurality of feedback channel occasions, the plurality of feedback channel occasions associated with the transmission received from the second UE over the first sidelink data channel in the first sub-band, the plurality of feedback channel occasions in a plurality of sub-bands, the UE operable to transmit, to the second UE, the feedback associated with the transmission using one or more of the plurality of feedback channel occasions; and 
 transmit, to the second UE, the feedback associated with the transmission over one or more feedback channel occasions of the plurality of feedback channel occasions based at least in part on performing the listen-before-talk for each of the plurality of feedback channel occasions. 
 
 
     
     
       26. The apparatus of  claim 25 , wherein the instructions to receive the control message including the configuration of the plurality of feedback channel occasions are executable by the processor to cause the apparatus to:
 receive the control message including the configuration indicating a plurality of feedback channel pools, each of the plurality of feedback channel pools corresponding to one sub-band of the unlicensed radio frequency spectrum band, wherein the plurality of feedback channel occasions includes one feedback channel pool of the plurality of feedback channel pools. 
 
     
     
       27. The apparatus of  claim 25 , wherein the instructions to receive the control message including the configuration of the plurality of feedback channel occasions are executable by the processor to cause the apparatus to:
 receive the control message including the configuration indicating an index associated with a second sub-band and an offset value between the first sub-band and the second sub-band, wherein the plurality of feedback channel occasions include a first feedback channel occasion located in the first sub-band and a second feedback channel occasion located in the second sub-band. 
 
     
     
       28. An apparatus for wireless communication at a user equipment (UE), comprising:
 a processor; 
 memory coupled with the processor; and 
 instructions stored in the memory and executable by the processor to cause the apparatus to:
 transmit, to a second UE, a control message including a configuration of a plurality of feedback channel occasions in a plurality of sub-bands of an unlicensed radio frequency spectrum band, the plurality of feedback channel occasions for feedback associated with a transmission and corresponding to a first sidelink data channel in a first sub-band of the unlicensed radio frequency spectrum band; 
 transmit, to the second UE, the transmission over the first sidelink data channel in the first sub-band of the unlicensed radio frequency spectrum band, the plurality of feedback channel occasions associated with the transmission transmitted to the second UE over the first sidelink data channel in the first sub-band, the UE operable to receive, from the second UE, the feedback associated with the transmission using one or more of the plurality of feedback channel occasions; and 
 receive, from the second UE, the feedback associated with the transmission over one or more feedback channel occasions of the plurality of feedback channel occasions based at least in part on a listen-before-talk for each of the plurality of feedback channel occasions, wherein the listen-before-talk for each of the plurality of feedback channel occasions is based at least in part on the configuration of the plurality of feedback channel occasions.